Power went out at 9:35am and was partially restored at around 12:30pm. Mymensingh and Sylhet region were however spared of the outage.

The massive loadshedding had its knock-on effects on water supplies, leaving millions of homes dry by noon. Dhaka Water and Sewerage Authority (Wasa) in a press release said it is trying to pump out water with 250 generators.

Industrial production screeched to a halt by noon as generators overheated. Even mobile telephone network faltered.

Functions in offices including the Prime Minister's Office, the parliament secretariat, business houses, banks and electronic media faced severe disruption.

Hospitals suspended scheduled operations, saving energy for emergency surgeries only.

Shopping malls and markets desperately tried to keep businesses open with generators, which also heated up to bring business to a standstill.

By 7:00pm, Power Development Board (PDB) engineers managed to put on grid 1900 MW against a peak demand of 3300 MW. Dhaka that consumes about 1400 MW sweated in darkness with only about 500 MW available.

Sources said it will take another day to restore full power supply.

Two committees-- a five-member one by the PDB and the other of three members by the power ministry -- have been formed to probe the incident. The committees have been asked to submit reports within 24 hours.

The trouble began when the biggest power plant -- the 450 MW AES Meghnaghat unit -- tripped at 9:35am due to a technical glitch in the transmission system.

"Power from different plants converge at the Ashuganj power grid. We suspect this grid tripped because of high voltage," said a source. "This might have affected the Meghnaghat plant."

The sudden shutdown of the Meghnaghat plant put tremendous pressure on other plants connected to the national grid. Within minutes, they also started tripping one after another.

Only Mymensingh and Sylhet regions remained online as two power plants there continued functioning independently.

But the 140 MW Rural Power Company Limited (RPCL) plant in Mymensingh and the Fenchuganj 90 MW power plant are too inadequate to act as emergency sources for important offices.

"As an immediate action, we tried to start auxiliary power systems of some major plants to take pressure off main plants for their restart. This has always worked, but this time it did not," said a PDB source.

Even though engineers started a 30 MW auxiliary system at Baghabari, the main plant tripped again as soon as it was connected to the national grid.

By 11:00am, the engineers made another abortive attempt to start an auxiliary system at Ashuganj. However, at around 11:30am, they succeeded to start the Ashuganj and Shahjibazar power systems and limited power supply resumed at important installations.

At the Secretariat and adjacent areas, power supply resumed at 12.35 noon and slowly to other areas of the capital. However, the supply remained erratic.

State Minister for Power Iqbal Hasan Mahmud blamed technical glitches for the power failure.

"We don't want to think of any subversive act. Our machinery is too old. This is totally related to technical matters and we can never say whether such things will happen in the future. But we will take measures to avoid such things," he said to the press.